Question

Image text transcribed for accessibility:A line in the hydrogen spectrum is measured in the laboratory to have a wavelength of 122 nm. This same line is identified in a distant galaxy, but has a wavelength of 300 nm. What is the relative velocity of that galaxy with our own galaxy. (You can neglect the motion of the Earth around the sun and the motion of the Sun around the galaxy center.) What wavelength would we measure if that same galaxy were moving toward us with the speed you found in part (a)?